This invention relates to pole changing single phase alternating current rotary electric machines, and more particularly to pole changing induction motors having stator windings capable of being connected for six-pole or eight-pole operation.
Dual capacity heat pumps and air conditioning units require dual speed fan and blower motors. In conventional fan or blower motors, a booster winding is connected in series with the main stator winding to provide a reduced level of flux within the motor. This results in lower speed operation through an increase in slippage but also results in lower efficiency at low operating speeds.
Pole changing alternating current motors have been developed to operate at multiple speeds by alternatively providing different pole numbers according to a method of phase winding switching known as pole amplitude modulation. For example, U.S. Pat. No. 3,233,160 issued Feb. 1, 1966 to Rawcliffe, discloses a pole changing single-phase alternating current winding arrangement for a rotary electric machine comprising two windings for connection together to a single-phase alternating current supply to provide a running field for the machine, where each winding is wound for a first pole number and includes winding parts arranged for alternative connection in the circuit according to the method of pole amplitude modulation, to provide second and third pole numbers together in each winding considered independently. An additional starting winding is provided for connection to the singe-phase alternating current supply through a phase shifting means to produce a starting field for the machine. The first two stator windings are physically disposed for elimination of the third pole number from the running field. U.S. Pat. No. 3,619,730 issued Nov. 9, 1971 to Broadway et al., discloses a four pole/six pole motor having a four-pole auxiliary winding.
To minimize noise, heat pump and air conditioning units have been designed to include a six-pole or eight-pole fan motor for air movement in the outdoor unit. This invention provides a single-phase alternating current motor having a six pole/eight pole stator winding arrangement which is suitable for use in fan and blower applications.